JP2824672B2 - Pneumatic tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic tire. More specifically, the present invention relates to a pneumatic tire with improved drainage of the tire.

[Conventional technology]

Conventionally, in general, in order to improve the drainage performance of a pneumatic tire, it is said that it is better to provide a circumferential straight groove in a center portion of a tread pattern and provide a lateral groove (lug groove) in a shoulder portion.

Further, in order to further improve drainage, a directional pattern in which lateral grooves are arranged in a V-shape over the entire width of the tire in contact with the tire is employed.

However, as described above, even if various grooves or directional patterns are employed, it is difficult to say that the drainage of the tire is always sufficient.

[Problems to be solved by the invention]

The present invention has been made in view of such a conventional problem, and an object of the present invention is to improve the drainage performance of a pneumatic tire, thereby achieving various performances such as a hydroplaning generation speed and a wet circular turning limit speed. The goal is to improve.

[Means for solving the problem]

That is, the pneumatic tire according to the present invention is a pneumatic tire provided with a plurality of main grooves extending in a tire circumferential direction on a tire tread surface and a lateral groove crossing the main grooves and extending from a center portion to a shoulder portion. The intersection point where the center line extending in the tire circumferential direction at the center of the tread width in the tire circumferential direction intersects with the front end line of the tread, and the line segment extending in the tire circumferential direction at a position separated from the center line by 40% of the tread width to the right and left, respectively, are The radius r of the approximate arc of the contact front end line defined by the arc including the front end line and the two intersections that intersect each other is determined by the contact width w
2w, and the direction of the main groove connecting the adjacent lateral grooves is set to an angle within ± 10 ° with respect to the normal of the approximate arc, and the main groove is In addition to the center part, it is also located on the shoulder part outside 40% of the contact width from the center of the tire tread.

Here, the front end line of the tire is defined as the pneumatic tire.
On the contact surface of the tire tread when a normal load of JATMA standard is applied, it refers to the boundary line between the front end portion of the contact surface and the non-contact surface in the traveling direction of the vehicle.

Further, the arc that approximates the contact front end line of the tire tread is an intersection point where a center line extending in the tire circumferential direction around the contact width center of the tire tread intersects with the contact front end line, and the contact width of the contact width is left and right from the center line, respectively. It is a circular arc including a line segment extending in the tire circumferential direction at a position separated by 40% and including two intersections each intersecting the front contact line with the ground.

By the way, when the tire mounted on the vehicle travels on a wet road surface, observing the draining direction of the water removed at the front contact end of the tire tread, it can be seen that the direction of the water is almost normal to the front contact line. Based on such findings, the present invention has a shape that allows the ground contact front of the tire tread to be efficiently drained, and sets the direction of the groove that greatly contributes to the drainage action.

In the present invention, the contact front end line of the tire tread needs to be set so that the radius r of the approximate arc defined above has a relationship of r ≦ 2w with respect to the contact width w. In other words, it is better that the front contact line of the tire of the present invention is as close to a circle as possible, so that the drainage effect at the front contact end is better. If the front end line is larger than 2 w, the contact surface becomes a square shape. As described above, the shape of the contact surface close to a square is inferior to the shape of the contact surface close to a circle in drainage effect at the front edge.

Further, in the present invention, the installation direction of the main groove connecting the adjacent horizontal grooves must be within ± 10 ° with respect to the normal line of the approximate arc. This reduces the flow resistance when draining from the groove at the front end of the tread of the tire tread,
The most efficient drainage can be performed.

Further, the main groove having the above-described installation angle condition exists in the entire tread surface including the center portion, and the contact width of the tread width from the center of the tire tread surface.
It must also be located on the shoulders outside of 40%.
As a result, efficient drainage is possible over the entire area of the tire tread before contact with the ground, and by improving the drainage performance, the running speed until hydroplaning occurs is increased, and the wet circular turning limit speed is improved, and the wet tread is improved. The steering stability of the vehicle can be improved.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a development view of a tread pattern of a pneumatic tire according to the present invention. In the center of the tread 1, a first main groove 2 that is linear in the circumferential direction of the tire is arranged.

Also, two types of transverse grooves 3 and 4 having different groove widths are alternately arranged one by one in the circumferential direction of the tire so as to cross the main groove 2.

Further, on both sides of the first main groove 2, second and third main grooves 5, 6 communicating with the lateral grooves 3, 4 are arranged. These two main grooves 5, 6 have a zigzag shape through a part of the lateral grooves 3, 4. The main groove 2 intersects with the lateral grooves 3 and 4 and the main grooves 5 and 6 communicate with the lateral grooves 3 and 4 to block the tread from the tread center portion 7 to the shoulder portion 8.
9, 10, and 11 block groups are formed. The groove width of the lateral groove 3 gradually decreases as moving from the left side to the right end of the tread 1, and the groove width of the horizontal groove 4 gradually decreases as moving from the right end to the left end of the tread 1.

Needless to say, the main groove 2 is arranged in the direction of the normal 13 of the approximate arc 12 described later, but the main grooves 5 and 6 are also lateral grooves.
In the section connecting 3 and 4, it is installed in the direction of the normal 13 of the approximate arc 12. When the tire steps on the film-like water surface due to such normal arrangement, the tire tread surface 14
The flow resistance at the time of drainage from the main grooves 2, 5, 6 at the front end 16 of the ground is minimized.

As shown in FIG. 2, the approximate arc 12 is formed by an intersection point a where a center line 15 extending in the tire circumferential direction at the center of the contact width of the tire tread surface 14 intersects with a front contact end line 16, and from the center line 15, respectively. Line segments 17 and 18 extending in the tire circumferential direction at positions separated by 40% of the width w are defined by arcs including two intersections b and c which intersect the ground front end line 16 respectively.
The radius r of the approximate arc 12 has a relation of r ≦ 2w with respect to the contact width w as described above.

The third main groove 6 has a width A of 40% of the tire contact width w.
Shoulder part 8 outside the tread center part 7 with
, So that water can be efficiently drained from the region of the shoulder portion 8. The main groove 2 is provided at the center of the tread 1, and the second main groove 5 is also arranged inside the tread center portion 7.

Now, when a tire having the above-described tread pattern is mounted on a passenger car and the vehicle is driven on a wet road surface, the film-like water covering the road surface is an approximate arc approximating the tire front contact line 16.
It is most efficiently bounced off in the direction of its normal 13 over the entire region of twelve.

Therefore, by improving the drainage performance of the tire, each performance such as the hydroplaning generation speed and the wet circular turning limit speed is further improved as compared with the related art.

Table 1 shows the results of evaluating and comparing the hydroplaning occurrence speed and the wet circular turning limit speed in the actual vehicle for the tire of the present invention, the conventional tire, and the comparative tire.

From this table, it can be seen that the tire according to the present invention has better hydroplaning occurrence speed and wet circular turning limit speed than the conventional tire and the comparative tire.

(A) Tire of the present invention As shown in FIG. 1, a tire in which a plurality of main grooves are oriented in the normal direction of an approximate arc approximating the contact front end of the tire tread.

(B) Conventional tire A tire in which the second and third main grooves 5, 6 are straight grooves parallel to the first main groove 2.

(C) Comparative tire A tire in which the second and third main grooves 5, 6 are inclined by an average of + 15 ° toward the tread side end with respect to the normal line of the approximate arc approximating the ground front end.

[Effects of the Invention] As described above, the present invention provides a pneumatic tire in which a plurality of main grooves extending in the tire circumferential direction and a lateral groove intersecting the main grooves and extending from a center portion to a shoulder portion are provided on the tire tread surface. , An intersection where a center line extending in the tire circumferential direction at the center of the contact width of the tire tread crosses the front end of the tire, and a line extending in the tire circumferential direction at a position left and right separated from the center line by 40% of the contact width, respectively. The radius r of the approximate arc of the ground contact end line defined by the arc including the two points of intersection with the ground contact front end and the intersections respectively, is defined as r ≦ r with respect to the ground contact width w.
2w, and the direction of the main groove connecting the adjacent horizontal grooves is set to an angle within ± 10 ° with respect to the normal of the approximate arc, and the main groove including the center portion is included. ,
Since the tires are also placed on the shoulders outside the contact width of 40% from the center of the tire tread, the drainage of the tires is further improved compared to conventional tires.

Therefore, various performances such as a hydroplaning generation speed and a wet circle turning limit speed are improved.

[Brief description of the drawings]

FIG. 1 is a development view of a tread pattern of a pneumatic tire according to the present invention, and FIG. 2 is an explanatory diagram of an approximate arc approximating a front contact line of the tire. 2,5,6 ... Main groove, 3,4 ... Horizontal groove, 7 ... Center part, 8 ...
… Shoulder part, 12… Approximate arc, 13… Normal line of approximate arc, 14… Tire tread, 15… Center line, 16… Ground front end line, 17,18 …… Line segment, a, b, c: intersection, w: contact width.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60C 11/04 B60C 11/00

Claims (1)

(57) [Claims] 1. A pneumatic tire having a plurality of main grooves extending in a tire circumferential direction on a tire tread surface and a lateral groove intersecting the main groove and extending from a center portion to a shoulder portion. And an intersection where a center line extending in the tire circumferential direction intersects with the ground contact front line, and a line segment extending in the tire circumferential direction at a position separated by 40% of the ground contact width from the center line to the left and right respectively intersects with the ground front end line. The radius r of the approximate arc of the ground contact front end line defined by the arc including the two intersections is set to a relation of r ≦ 2w with respect to the ground contact width w,
And the direction of the main groove connecting the adjacent lateral grooves is set to an angle within ± 10 ° with respect to the normal line of the approximate arc, and the main groove including the center portion, from the center of the tire tread surface. A pneumatic tire placed on the shoulder outside 40% of the contact width.